Sen. Jim DeMint plunged $200,000 into the Club for Growth super PAC just before the group helped topple his Republican colleague Dick Lugar in the contentious Indiana primary.

The South Carolina Republican’s campaign committee has donated at least $700,000 to the conservative super PAC this cycle, according to the latest federal filings released Thursday. His initial $500,000 contribution in February irked top Republicans on Capitol Hill after DeMint had promised he wouldn’t try to unseat fellow GOP senators in their primaries this cycle.

DeMint earlier this year denied that his donations were meant to undermine Lugar, saying his leadership PAC and the Club for Growth were aligned in Wisconsin, Nebraska, Texas and Ohio — races where there are no Republican incumbents.

The Club for Growth Action super PAC was the biggest spender in the pricey air wars that dominated the Indiana primary, according to data compiled by the Center for Responsive Politics. The group spent about $1.5 million on ads in the Hoosier State that helped fuel tea-party-backed Indiana state Treasurer Richard Mourdock’s victory over Lugar last week.

Club for Growth Action spent a total of $2.2 million to run ads last month in Indiana, Nebraska and North Carolina. Those ads included attacks on Nebraska Attorney General Jon Bruning before he lost the GOP Senate primary to tea party favorite state Sen. Deb Fischer, as well as ads to boost North Carolina congressional candidate Scott Keadle.

DeMint also poured $1.4 million from his leadership PAC into the Nebraska race to boost another GOP candidate, Don Stenberg. DeMint’s involvement was credited with helping to defeat Bruning, the establishment favorite, and it drew the rebuke of Nebraska Republican Sen. Mike Johanns.